Ekstrakcija proteina iz toplinski stabilnih nemasnih rižinih mekinja fermentacijom heterofermentativnih mikroorganizama na čvrstoj podlozi pomoću tradicionalnih azijskih startera

Research background. Heat-stabilised defatted rice bran (HSDRB) is a primary by-product of rice bran oil extraction industry and a nutritious source of protein. However, despite the unique nutritional profile of rice bran protein, the protein-rich by-product, HSDRB is underutilised as a low-value animal feed. Research on protein extraction from HSDRB by enzymatic hydrolysis has attracted the attention of numerous scientists. However, a cost-effective extraction method is required to mitigate the high costs associated with the use of enzymes. Therefore, we have presented an alternative economical and natural approach for protein extraction from HSDRB by solid-state fermentation (SSF) with heterofermentative microbes. Experimental approach. SSF of HSDRB with two types of traditional Asian fermentation starters, namely loog-pang and koji, were evaluated for enzyme production and their efficacy in extracting proteins from HSDRB. For this purpose, HSDRB fermentation was carried out for 0, 12, 24, 48, 72 and 96 h followed by 24-hour hydrolysis to evaluate the extracted rice bran protein. In addition, microbiome diversity in the fermentation starters was also determined by metagenomic sequencing of 16S rRNA and internal transcribed spacer to identify bacteria and fungi, respectively. Results and conclusions. The microbial community in the fermentation starters showed the dominance of lactic acid bacteria (LAB) such as Bacillus subtilis in loog-pang and Streptococcus lutetiensis, Bacillus pumilus, Lactococcus cremoris, Lactococcus garvieae and Pediococcus pentosaceus in koji, while yeast species Saccharomycopsis fibuligera and Saccharomyces cerevisiae dominated the fungal diversity in loog-pang and koji starters, respectively. The results suggest that loog-pang and koji can produce cellulase, neutral and acid proteases during fermentation. Despite the discrepancy in their microbial diversity and the enzyme activity during SSF, both starters could effectively increase protein extraction from HSDRB. A positive relationship between the SSF duration and extracted protein was observed. During SSF with loog-pang and koji after 72 h followed by 24-hour hydrolysis, 65.66 and 66.67 % protein was extracted from HSDRB, respectively. The amino acid analysis of the protein hydrolysate produced by the non-fermented and fermented methods showed no difference and had an abundance of glutamic and aspartic acids, leucine, arginine, alanine and glycine amino acids, which accounted for approx. 58 % of the total amino acids. Novelty and scientific contribution. Loog-pang and koji (traditional Thai and Japanese fermentation starters, respectively) were found to be effective in extracting proteins from HSDRB by SSF although they are inexpensive microbial enzyme sources. Future research aimed at scaling up HSDRB protein extraction for usage in industrial applications can draw on our results.Pozadina istraživanja. Toplinski stabilne nemasne rižine mekinje su glavni nusproizvod ekstrakcije ulja iz rižinih mekinja, te su bogat izvor proteina. Međutim, usprkos jedinstvenim hranjivim značajkama, taj nusproizvod bogat proteinima je slabo iskorišten i koristi se samo kao stočna hrana male vrijednosti. Sve je veći interes znanstvenika za ispitivanje ekstrakcije proteina iz toplinski stabilnih nemasnih rižinih mekinja enzimskom hidrolizom. Međutim, za to treba razviti ekonomičnu metodu kojom bi se smanjili veliki troškovi uzrokovani primjenom enzima. Stoga u radu predlažemo alternativni ekonomičan i prirodni postupak ekstrakcije proteina iz nemasnih rižinih mekinja fermentacijom heterofermentativnih mikroorganizama na čvrstoj podlozi. Eksperimentalni pristup. Ispitan je postupak proizvodnje enzima i ektrakcije proteina fermentacijom toplinski stabilnih nemasnih rižinih mekinja na čvrstoj podlozi pomoću dva tradicionalna azijska startera, loog-pang i koji. Stoga su mekinje fermentirane tijekom 0, 12, 24, 72 i 96 h, a zatim je provedena hidroliza tijekom 24 sata za procjenu izdvojenog proteina. Osim toga, određena je mikrobiološka raznolikost startera metagenomskim sekvenciranjem 16S rRNA za identifikaciju bakterija i sekvenciranjem transkribiranih internih razdjelnih zona za identifikaciju kvasaca. Rezultati i zaključci. U mikrobnoj kulturi startera loog-pang prevladavale su bakterije mliječno-kiselog vrenja poput Bacillus subtilis, dok su u starteru koji prevladavale bakterije Streptococcus lutetiensis, Bacillus pumilus, Lactococcus cremoris, Lactococcus garvieae i Pediococcus pentosaceus. Kvasac Saccharomycopsis fibuligera prevladavao je u starteru loog-pang, a Saccharomyces cerevisiae u starteru koji. Rezultati pokazuju da starter kulture loog-pang i koji tijekom fermentacije proizvode celulazu, te neutralne i kisele proteaze. Usprkos različitom mikrobiološkom sastavu i aktivnosti enzima tijekom fermentacije na čvrstoj podlozi, primjenom se obje starter kulture uspješno povećala ekstrakcija proteina iz rižinih mekinja. Opažena je pozitivna korelacija između trajanja fermentacije i ekstrakcije proteina. Nakon 72 h fermentacije i 24 h hidrolize, u podlozi s loog-pang starterom iz rižinih je mekinja izolirano 65,66 % proteina, a u podlozi s koji starterom 66,67 % proteina. Usporedbom aminokiselinskog sastava proteinskih hidrolizata dobivenih fermentacijom i metodom bez fermentacije nisu utvrđene razlike među njima, a glutaminska i asparaginska kiselina, leucin, arginin, alanin i glicin činile su otprilike 58 % ukupnih aminokiselina. Novina i znanstveni doprinos. Tijekom fermentacije na čvrstoj podlozi pomoću tradicionalnog tajlandskog startera loog-pang i tradicionalnog japanskog startera koji učinkovito su izolirani proteini iz toplinski stabilnih nemasnih rižinih mekinja, iako se one smatraju jeftinim izvorom mikrobnih enzima. Dobiveni rezultati mogu biti korisni za buduća istraživanja ekstrakcije proteina iz rižinih mekinja u industrijskim uvjetima

Chemical profiles of three varieties of germinated rice based on LC-MS and their antioxidant activity

In this study,chemical profiles in different germinated rice extracts (GREs) using different solvent extraction ratio were investigated.Three varieties of germinated rice (GR), including germinated white rice(GWR), germinated black rice (GBR) and germinated red rice(GRR) were extracted using 70and 100% ethanol(v/v). Both extracts were characterized for their chemical profiles using liquid chromatography-electrospray ionization−quadrupole−time−of−flight mass spectrometry (LC−ESI−Q−TOF−MS). The content of γ−aminobutyric acid (GABA), total phenolic content (TPC), and antioxidant activities were also determined. The chemical profiles of GREs are composed of organic acids, amino acids, vitamins, flavonoids,and phenolic compounds. The GABA content of all rice varieties presented the same pattern in both ethanolic extracts. The TPC of GRE extracted by 70% ethanol (v/v) showed significant higher amount than that in the 100%v/vethanolic extract(p<0.05). The highest TPC was obtained from GBR, followed by GRR and GWR, respectively(p<0.05). The antioxidant activity from three assays, including DPPH, ABTS, and FRAP showed higher activities in the 100% v/vethanolic extracts than their 70% v/v counterparts(p<0.05). The phenolic content showed a low positive Pearson correlation with antioxidant activities, however,the strong positive Pearson’s correlation coefficients were observed among these activities (r= 0.846-0.935). The results suggested that the GR was composed of potential bioactive compounds such as GABA and other phytochemical contents possessing high antioxidant bioactivity which can be used as functional food or as part of nutraceutical products

Heat inactivation and reactivation of broccoli peroxidase. Jourrnal of agricultural and food chemistry

Heat inactivation characteristics differed for acidic (A), neutral (N), and basic (B) broccoli peroxidase. At 65°C, A was the most heat stable followed by N and B. The activation energies for denaturation were 388, 189, and 269 kJ/mol for A, N, and B, respectively. Reactivation of N occurred rapidly, within 10 min after the heated enzyme was cooled and incubated at room temperature. The extent of reactivation varied from 0 to 50% depending on the isoenzyme and heating conditions (temperature and time). The denaturation temperature allowing the maximum reactivation was 90°C for A and horseradish peroxidase (HRP) and 70 and 80°C for B and N, respectively. In all cases, heat treatment at low temperatures for long times prevented reactivation of the heated enzymes. Calcium (5 mM) increased the thermal stability of N and B but had no effect on reactivation. The presence of 0.05% bovine serum albumin decreased thermal stability but increased the extent of reactivation of A.

Subcritical liquified dimethyl ether and supercritical fluid carbon dioxide extraction of gamma oryzanol from rice bran acid oil

Gamma oryzanol (γ-oryzanol) is a bioactive compound in rice bran acid oil, a by-product of the rice bran oil refining process that possesses various pharmacological properties. This study investigated the effect of green technology supercritical fluid carbon dioxide extraction (SF–CO2) and subcritical liquified dimethyl ether extraction (SUBLDME) of γ-oryzanol from rice bran acid oil. Results showed that subcritical liquified dimethyl ether extracted oryzanol at 4865.25 mg/100 g from rice bran acid oil without pretreatment by hexane and ethyl acetate compared with supercritical fluid carbon dioxide extraction (2569.04 mg/100 g), with high extraction efficiency (62.73 vs 18.86%). Further extraction of the filter cake remaining from supercritical fluid carbon dioxide extraction from rice bran acid oil without pretreatment using subcritical liquified dimethyl ether extraction gave the highest percentage yield and γ-oryzanol contents (8128.51 mg/100 g). Supercritical fluid carbon dioxide extraction together with subcritical liquified dimethyl ether extraction showed promise as a green technology to extract γ-oryzanol from rice bran acid oil. Further studies are required to optimize both SF-CO2 and SUBLDME extraction methods to increase the γ-oryzanol content

Nutraceutical Difference between Two Popular Thai Namwa Cultivars Used for Sun Dried Banana Products

Musa (ABB group) &ldquo;Kluai Namwa&rdquo; bananas (Musa sp.) are widely grown throughout Thailand. Mali Ong is the most popular Kluai Namwa variety used as raw material for sun-dried banana production, especially in the Bangkratum District, Phitsanulok, Thailand. The sun-dried banana product made from Nanwa Mali Ong is well recognized as the best dried banana product of the country, with optimal taste compared to one made from other Kluai Namwa varieties. However, the production of Mali Ong has fluctuated substantially in recent years, leading to shortages. Consequently, farmers have turned to using other Kluai Namwa varieties including Nuanchan. This study investigated the nutraceutical contents of two popular Namwa varieties, Mali Ong and Nuanchan, at different ripening stages. Nutraceuticals in the dried banana products made from these two Kluai Namwa varieties and four commercial dried banana products were compared. Results indicated that the content of moisture, total sugar, and total soluble solids (TSS) (&deg;Brix) increased, while total solids and texture values decreased during the ripening stage for both Kluai Namwa varieties. Rutin was the major flavonoid found in both Namwa Mali Ong and Nuanchan varieties ranging 136.00&ndash;204.89 mg/kg and 129.15&ndash;260.38 mg/kg, respectively. Rutin, naringenin, quercetin and catechin were abundant in both Namwa varieties. All flavonoids increased with ripening except for rutin, gallocatechin and gallocatechin gallate. There were no significant differences (p &lt; 0.05) in flavonoid contents between both varieties. Tannic acid, ellagic acid, gallic acid, chlorogenic acid and ferulic acid were the main phenolic acids found in Mali Ong and Nuanchan varieties, ranging from 274.61&ndash;339.56 mg/kg and 293.13&ndash;372.66 mg/kg, respectively. Phenolic contents of both varieties decreased, increased and then decreased again during the development stage. Dopamine contents increased from 79.26 to 111.77 mg/kg and 60.38 to 125.07 mg/kg for Mali Ong and Nuanchan, respectively, but the amounts were not significantly different (p &lt; 0.5) between the two Namwa varieties at each ripening stage. Inulin as fructooligosaccharide (FOS) increased with ripening steps. Production stages of sun-dried banana products showed no statistically significant differences (p &lt; 0.05) between the two Namwa varieties. Therefore, when one variety is scarce, the other could be used as a replacement in terms of total flavonoids, phenolic acid, dopamine and FOS. In both Namwa varieties, sugar contents decreased after the drying process. Sugar contents of the dried products were 48.47 and 47.21 g/100 g. The drying process caused a reduction in total flavonoid contents and phenolic acid at 63&ndash;66% and 64&ndash;70%, respectively. No significant differences (p &lt; 0.05) were found for total flavonoid and phenolic contents between the dried banana products made from the two Namwa varieties (178.21 vs. 182.53 mg/kg and 96.06 vs. 102.19 mg/kg, respectively). Products made from Nuanchan varieties (24.52 mg/kg) contained significantly higher dopamine than that from Mali Ong (38.52 mg/kg). The data also suggest that the banana maturity stage for production of the sun dried products was also optimum in terms of high nutraceutical level